July 26, 2011

The serendipitous discovery of a collision ring galaxy, identified as 2MASX J06470249+4554022, dubbed 'Auriga's Wheel', was found in a SUPRIME-CAM frame as part of a larger Milky Way survey. The ring has a radius of about 10 kpc and a bridge of stars and gas connecting two galaxies.

The collision causes gas to collapse and results in a burst of star formation in the ring. In Auriga's Wheel, only 50 million years old, gas flows into the center, pouring fuel onto the central black holes and resulting in the active galaxies.

Institute for Astronomy in Germany noticed the rare galaxy in their image they tentatively dubbed it “Auriga’s Wheel." The redshift of these objects would allow astronomers to explore their distance and confirm that they were likely interacting and not simply a chance alignment. When the data was analyzed, the galaxies were found to lie together at a distance of nearly 1.5 billion lightyears making this a new record holder for furthest ring galaxy.

Auriga's Wheel as seen in the g (left) and r (right) filters from Subaru. But aside from the temporary place in the record books, the pair is interesting in other ways. Modeling of the interaction as well as the spectroscopic data allowed the team to estimate the propagation of the ring to be at ~200 km/sec which would make it 50 million years since the collision occurred. The image also clearly shows the galaxy that plunged through the center of the more massive, disk galaxy and a distinct trail of gas and dust connects the two. Additionally, both galaxies appear to have Active Galactic Nuclei, which is rare for ring galaxies. However, it is not clear whether the activity was a result of the collision or a property of the individual galaxies prior to the interaction.